1. Field of the Invention
The present invention relates to an injection instrument for injecting medicinal fluid or the like into the human body through a catheter or other tubular injection instrument under the action of ultrasonic vibration at the injection site for improving diffusion and penetration of the injected medicinal fluid or the like. It is noted that in this specification, the term "injection" means injection of medicinal fluid or the like, unless otherwise specified.
2. Prior Art
Therapy for and prophylaxis against human disease generally comprises both oral and parenteral administration by means of injections, oral applications, suppositories, percutaneous applications, and other means. Particularly, methods for injecting directly into the body include local injection, intraarterial and intravenous injection, and in addition the method of injecting medicinal substance into target sites through an intravascular catheter, or the like.
With these methods of introducing medicinal substances directly into the body, there are some difficulties with diffusing and penetrating into the body tissues. As a countermeasure against this, chemical methods have mainly been used.
With special regard to the utilization of ultrasonic waves for improved diffusion and penetration of medicinal fluid administered through a catheter, the present inventor invented a vascular system cleaning instrument designed to transmit ultrasonic vibration generated at its proximal part which is attached to a catheter (Japanese Unexamined Patent Publication (KOKAI) No. 52071/1981).
The prior art technique of utilizing ultrasonic waves for improved diffusion and penetration of medicinal fluid administered, for example, through a catheter into the vascular system, especially to the retained substance therein, has difficulty in exhibiting a sufficient effect due to the damping of ultrasonic energy in the course of transmission. This is because the ultrasonic oscillating element is located outside the human body and far from the distal end of the catheter.